This research proposal is to study the interaction between secretin, glucose and arginine stimulated insulin responses in man. This interaction will be investigated by the administration of secretin in combination with either glucose or arginine in normal and diabetic subjects as well as subjects with chronic pancreatitis. This interaction will also be evaluated by immunoassay measurement of plasma secretin to known stimuli. The relationship of plasma secretin to direct stimulation of insulin release and to potentiating insulin responses of glucose and arginine will be carefully defined. The regulation of endogenous secretin release and its insulin stimulating properties by alterations of adrenergic and cholinergic activity will be evaluated.